Based on 2007 estimates, 16.5 percent of American Indians and Alaska Natives suffer from the disease. That's more than twice the national average of 7.8 percent.

Among racial and ethnic groups, Native Americans ranked the highest. The rate among African-Americans was 11.8 percent, followed by Hispanics at 10.4 percent.

In contrast, only 7.5 percent of Asian Americans suffered from diabetes. And only 6.6 percent of Whites were diagnosed with the disease.

Overall, the CDC estimates that nearly 24 million people are affected by diabetes. The figure represents a 3 million increase in the last two years.

"It is concerning to know that we have more people developing diabetes, and these data are a reminder of the importance of increasing awareness of this condition, especially among people who are at high risk," said Dr. Ann Albright, director of the CDC Division of Diabetes Translation.

Tribal affiliation played a role in the risk to Native Americans. Among Alaska Natives, for instance, only 6.0 percent suffered from diabetes.

But among tribes in southern Arizona, 29.3 percent of adults are diagnosed with the diseases. Pima tribes in the state suffer from one of the highest rates of diabetes in the world.

In New Mexico, the diabetes rate in counties with large Navajo populations was higher than counties with large Pueblo and Apache populations. In South Dakota, nearly every county that is home to a reservation had a diabetes rate higher than 10 percent.

In Montana, Big Horn County had the highest rate in the state -- 12.3 percent of the population has diabetes. The county is home to the Crow Reservation.

Besides Alaska, the only other state with a diabetes rate that was lower than the national average was Colorado. The state is home to two Ute tribes.

Diabetes can have costly effects. It's the nation's seventh leading killer, according to data from 2006.

Diabetes can also contribute to heart disease, stroke, high blood pressure, blindness and kidney disease.

Despite the disparity in Indian Country, health experts have claimed success in the war against the disease. Through programs funded by the Congressionally-authorized Special Diabetes Program for Indians, tribes have been able to address some key health indicators in the last decade.

With additional funding, tribes hope to do even more. They are asking Congress to authorize $200 million a year over the next five years, up from $150 million a year currently provided through Indian Health Service grants.

"Eight years is not enough time to turn around the rates of diabetes," Buford Rolin, the chairman of the Poarch Band of Creek Indians of Alabama, said at a Senate hearing in February 2007. "Give us time."

The Senate has been considering a Medicare bill that includes $150 million a year for the diabetes program. But Democrats and Republicans have been unable to agree on the overall Medicare bill, according to the National Indian Health Board.